Hypertension, internet use, physical activity, and dementia risk in older adults: A multinational prospective cohort...

Dementia is the fifth leading cause of death globally and currently has no cure. The evidence on the associations of hypertension, internet use, physical activity (PA) and dementia remains sparse.

This study examined whether internet use and PA mediate the hypertension-dementia link, assessed their interactive and joint effects with hypertension, and evaluated the direct, indirect, and total associations among these factors.

This multinational cohort study used data from four nationally representative surveys across 31 countries (2011-2024). We included participants aged 50 years or older with data on hypertension, PA, internet use, and at least two assessments, excluding those with baseline dementia or memory disease, missing dementia or covariate data, or lost to follow-up. The analytical sample comprised 57,912 participants with a mean follow-up of 7 years, during which 4,945 dementia endpoint events were recorded. We used Cox proportional hazards models to examine the hypertension-dementia association, and did subgroup analyses to explore the variation. Furthermore, we conducted interaction, longitudinal mediation, and joint effect analyses to assess relationships among hypertension, PA, internet use, and dementia risk. Finally, we pooled results using random-effects meta-analysis.

Hypertension was associated with increased dementia risk (hazard ratio[HR] 1.21 [1.11-1.31]). A significant multiplicative interaction existed between hypertension and internet use (HR 1.21 [1.06-1.38]). Longitudinal mediation analysis estimated indirect associations via PA (HR 1.06 [1.04-1.08]) and internet use (HR 1.21 [1.03-1.42]), with mediated proportions of 4.95% and 11.27%, respectively. Participants with hypertension, physical inactivity, and no internet use had a higher risk of dementia (HR 3.61 [3.21-4.06]). All associations were statistically significant (P < 0.05).

PA and internet use only partially mediate hypertension and dementia, indicating additional interventions may also be needed to reduce dementia risk in older adults. Furthermore, their joint effects with hypertension suggest the potential value of combined strategies to alleviate the global dementia burden.